True, meristem cells are undifferentiated
What part of the brain is the arrow pointing to? the cerebrum.
The general meaning of corpus means body in Latin. For example Habeas Corpus pretty much means "show me the body".
This figure illustrates 3 hypotheses of how a cancer stem cell may arise: (1) A stem cell undergoes a mutation, (2) A progenitor cell undergoes two or more mutations, or (3) A fully differentiated cell undergoes several mutations that drive it back to a stem-like state.